Crazy sg question

gww1gww1 Solar Expert Posts: 963 ✭✭
A page from gb battery.

My battery has one cell that runs about .020 lower then the high cells.

This is on discharge and charge.

Example. I eq last night and at 80 degrees the low cell was 1.275 and the high cell was above 1.300.
I woke this morning and the trimetric said that 130 amps had been removed from the battery and it was at 82% soc.
I took sg reading and the high cell was 1.260 and the low cell was 1.240.

The battery has on it that full is when the cells are 1.285 to 1.295.

Is it crazy to think about when it is time to water the batteries, to take a little electrolite from those cells that go above 1.300 and use to fill the low cell and try to even the sgs out? If I did it slowly and just a bit at a time through several months I could maby get the sgs close to factory spec and it would help my capasity over all and make it not quite as stressful on the low cell everytime I discharge cause the discharging would be shallower on it then it currently is.

The site I posted said to suppliment a low cell with 1.600 acid and that it needs to be done in lab conditions.

I am just curious in making it a bit better and slightly more equal between the cells. I may not have treated my battery perfectly but did treat all the cells the same and this one should have reacted as the others did making me believe the consetrate was off from the beginning. The over 1.300 seem to have a higher then spec consintration. Maby the battery was built on a friday or monday and the builders had blurry eye from the weekend and didn't pay quite as much attentions to the fill levels in the cells.

Is this crazy?
Thank you


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Crazy sg question

    Not recommended.

    The reason being you don't know why that one cell is consistently low. It could be incorrect electrolyte mixture, which can be corrected by altering the mix. But it could also be sulphation in one cell only, in which case raising the SG by adding acid will increase the rate at which the sulphates further. It could also be a defect in the plate manufacture that causes that cell to be slightly different resistance than the others, enough to affect SG all the time.

    If you can access the (+) and (-) terminals of the particular cell you can try EQ on that cell only and see if it makes a difference. But this is not easy to do. If you don't have a variable power supply to attach just to that one cell and push only its Voltage up (while doing nothing with the battery as a whole) you have to use a 6 Volt auto charger & Voltmeter & switch - and a lot of time watching it like a hawk turning the charger on/off to make sure the cell Voltage doesn't climb too high.

    On the whole, if the system works don't worry about one cell being off all the time even by that much. Trying to correct it can be more trouble than it's worth and may make matters worse.
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: Crazy sg question

    Thanks, Basically the system works fine for me. It is bothering that when I discharge to a 60% soc that that cell is basically dead per sg but it doesn't seem to heat up or really cause any bad affects when recharging and I don't discharge that deep to often as the lvd drops the battery with about 260 to 280 amps used. I just thought that it might be hard on that spicific cell always going so low. I know if worst comes to worst and that cell fails I could just replace it. But the batts are 1 and 1/2 years old now and it might hurt the other cells if I wait 3 or 4 years and have to do it.

    It seems to go up and down at the .020 point very consistantly and is not causing real problims now.

    If it is as good as I can expect, I really don't mind that much. I just worry that I don't know what I am doing and am making things worse.

    Thank you for your responce.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Crazy sg question

    gww1, I would talk to the supplier and see what they think is going on.
    You may be right about replacement at this time rather than later.
    KID #51B  4s 140W to 24V 900Ah C&D AGM
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    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: Crazy sg question

    I have talked to them and their view is that the plates may still not be formed yet but also that that might be the cell that goes first. They are sayng use the heck out of it but baby that cell a bit. In other word don't go below th 1.170 sg on that cell. They basically said that they have to deal with thousands of batteries and most every one has one cell that is not as good as the rest. Their advice has helped me with the rest of the battery sg though I say that almost all of the advice was to try a higher voltage. I must say that the batteries are easier to charge with the higher voltages. They have not wanted to think of it is a warrenty issue and I have not pushed it and probly won't unless it fails dramatically. If I replaced the cell I would probly just buy one and try to do it myself which would definatly void any warrenty. I got no warrenty papers, just what is implied on their web site.

    I will probly just live with it and learn while I go. If I make any kind of move it will probly be a self help type of move though I will ask their advice before doing it.

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